Field of the Invention
The present invention relates to a fixing device and an image forming apparatus including the same. The fixing device fixes a toner image to a recording medium by heating and pressing the recording medium with transferred toner image between a heat fixing member and a pressure member opposed to this heat fixing member. Particularly, the invention is directed to an effective utilization of the heat of the heat fixing member so as to achieve adequate reduction of the power consumption of the fixing device.
Description of the Related Art
In electrophotographic image forming apparatuses such as copiers, printers, facsimiles and multi-functional peripheries thereof, an operation is commonly performed to transport the recording medium with transferred toner image from an image carrier such as a photoreceptor to the fixing device, which fixes the toner image to the recording medium.
Such a fixing device generally has an arrangement where the toner image is fixed to the recording medium by heating and pressing the recording medium with transferred toner image between the heat fixing member and the pressure member opposed to this heat fixing member.
However, the conventional fixing devices have the following problem. The fixing device does not effectively utilize the heat of the heat fixing member serving to heat and press the recording medium with transferred toner image, and releases the heat to the outside. Thus, the fixing device fails to reduce the power consumption. Further, the surrounding temperature of the fixing device is raised by the heat released as described above, adversely affecting image formation.
Heretofore, there is known a fixing device which prevents vapor occurring in the heat fixing process from leaking from the fixing device while condensing the vapor for easy moisture removal and reduction of extra exhaust heat. That is, the fixing device achieves resource saving and is less likely to degrade office environment. As suggested in Patent Document 1 (JP-A No. 2006-58695), such a fixing device is provided with a cover member for covering a transport path for the recording medium. Disposed in this cover member is fixing means including the heat fixing member and pressure member which heat and press the recording medium with transferred toner image. Air containing the vapor occurring in the heat fixing process is sucked by air suction means and circulated in a circulation flow path of a reflux duct such that the heat of the vapor-containing air circulated through the circulation flow path is released to the outside by means of heat releasing means.
However, even the fixing device disclosed in the patent document 1 fails to effectively utilize the heat of the heat fixing member. The problem of the fixing device that cannot achieve the reduction of power consumption and such still remain unsolved.
The fixing device as described above may adopt the following structure for effective utilization of the heat of the heat fixing member for heating and pressing the recording medium with transferred toner image. The structure is made such that a fixing-member housing is disposed on an outer peripheral side of the heat fixing member while a reflection member is attached to an inner side of this fixing-member housing opposed to the heat fixing member. The reflection member reflects the heat released from the heat fixing member so as to enhance heat retention of the heat fixing member. Thus, the fixing device is reduced in the power consumption.
However, the following problem is encountered by the fixing device where the toner image is fixed to the recording medium by heating and pressing the recording medium with transferred toner image between the heat fixing member and the pressure member opposed to this heat fixing member. This image fixing operation entails the generation of foreign substances including volatile organic compounds (VOC), ultrafine particles (UFP), toner powder, paper dust and the like. These foreign substances adhere to a surface of the reflection member on the inner side of the fixing-member housing and hence, the heat released from the heat fixing member is not reflected but absorbed by the adherent foreign substances. Accordingly, the heat fixing member cannot be fully improved in the heat retention, making it difficult to fully reduce the power consumption of the fixing device.